1. Field
This application relates generally to wireless communication and more specifically, but not exclusively, to a messaging scheme for controlling transmit power of a wireless device.
2. Introduction
An electronic device may support one or more communication technologies to transmit information to and receive information from other electronic devices. For example, a wireless device may support wireless technologies such as WiMAX, WiFi, and CDMA to communicate over airwaves with another device.
In a wireless device, the selection of a power level at which signals are transmitted may be based on various factors. For example, when a signal is transmitted at a higher transmission power, an associated receiving device may more readily recover any data transmitted via that signal. However, transmitting at high power levels may cause interference at neighboring wireless devices and may result in reduced battery life for the transmitting device (e.g., for a mobile device).
In view of the above, various schemes have been developed in an attempt to maintain an optimum balance between high quality transmissions and acceptable transmit power levels. For example, the IEEE 802.16 standard describes a power scheme where a subscriber station may determine transmit power for a reverse link using either a closed loop power control procedure or an open loop power control procedure. Under closed loop power control, a base station transmits power control messages to the subscriber station and the subscriber station selects the transmit power level specified by these messages. Under open loop power control, the subscriber station selects a transmit power level based on a power control equation. Here, the subscriber station may determine some of the parameters for the power control equation on its own and may obtain other parameters from the base station.